Over the past few decades, there has been a rapid growth in both innovative techniques and commercially available instruments for performing full-field strain measurements by optical means. The need for procedures that would allow the calibration of such systems and for methodologies for comparing their performances either against one another or a manufacturer's specification has been recognized for some time. This led to the formation of the international Technical Working Area (TWA26) on full-field optical methods of strain measurement under the auspices of VAMAS in the late 1990s. A little later a European consortium of research labs, instrument designers and manufacturers and end-users was formed and obtained funding to develop a prototype standard to address this need. In 2006 the consortium published a draft standard for the calibration and evaluation of optical systems for strain measurement. This paper will provide a brief overview of the draft standard including an explanation of the different approaches taken to calibration and evaluation. These are based on the requirement to form a continuous chain of comparison to a national standard for calibration and the demand to assess the most advanced features of the most sophisticated instrument in the case of evaluation. The manner in which these requirements drove the design philosophies employed in the reference material and standardized test material will also be described. An example will be used to illustrate the calibration of a system and quantification of the uncertainty and confidence levels associated with the data subsequently acquired using the calibrated instrument. The introduction of these "standard" methodologies represents a substantial step in the development of reliable instrumentation operating within well-defined limits.

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Abstract: A novel phase unwrapping method with a hybrid of phase discontinuity marking, branch cut generation, and regional phase unwrapping is proposed. With this newly developed algorithm, quite noisy map coupled with real physical discontinuities can also be retrieved accurately and efficiently. A well-known simple wrapped map filter is used for filtering out most of the noise induced inconsistencies and leaving the phase discontinuities clearly shown on the map. The proposed algorithm is practically applied to an ESPI wrapped map for out-of-plane deformation detection. The practical unwrapping result reveals that the proposed method is effective for the phase unwrapping of ESPI work with real physical discontinuity.

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A new method for eliminating zero-order image and reconstructing the original image with high quality is described in this paper. In this method, the differential of the detected hologram intensity is used instead of the hologram itself for numerical reconstruction by computing the discrete Fresnel integral. This method is based on digital image processing free of any extra optical element. It can improve the image quality significantly and give better resolution and higher accuracy of the reconstructed image. The main advantages of this method are its simplicity in experimental requirements and convenience in data processing. The theoretical analysis is given and experimental results are presented.

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In order to measure three-dimensional displacement components of small objects such as a MEMS, the windowed phase-shifting digital holographic interferometry (Windowed PSDHI) previously developed by the authors is applied to a microscope. Three object laser beams in the optical system are used. Four phase-shifted holograms are recorded for each object laser beam. The complex amplitude of each reconstructed beam at the object is calculated by the Fresnel diffraction integral of the complex amplitude of the hologram. The reconstructed distance is obtained at the point with the maximum of the standard deviation of the intensity of the object reconstructed with changing the reconstruction distance. The three phase-difference values between before and after deformation provide the three-dimensional displacement components. The theory and applications are shown.

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The foundation and technical procedure of Nano-Pattern Recognition and Correlation Technique (N-PRCT) is described. The proposed technique is an in-plane displacement measurement technique that is based on regularly oriented structures. Displacement is obtained by tracking the movement of each single pattern in the images taken before and after loading (deformation) through techniques of pattern recognition and correlation. The proposed technique is insensitive to the noise involved in the digital images which comes inherently from the SEM imaging process; this results in high measurement accuracy. The technique provides the spatial resolution of less than 5 nm/pixel and displacement measurement accuracy of approximately 0.1 nm, which will be suited ideally for thermal deformation measurements of Low-K layer.

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Calibration is important to perform accurate shape measurement using a grating projection. It is required to calculate spatial coordinates from the phase value of a projected grating in short time for real-time shape measurement. We propose a calibration method using multiple reference planes. This method excludes a lens distortion and intensity errors of a projected grating in measurement results theoretically. Tabulation of relationship between phase values and spatial coordinates for each pixel makes short-time measurement possible. This calibration method is applied to the real-time shape and deformation measurement.

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Laser scanning confocal microscopy (LSCM) has been extensively used for image capturing and analysis in the field of bio-engineering as an advanced scientific instrument. It can achieve high spatial resolution (the horizontal resolution is about 0.2μm), and obtain extremely high-quality images from test specimens. By integrating LSCM and the existing scanning moire technique, a novel class of moire method, i.e., LSCM moire method is studied by experiments in this paper. The principle and condition of forming LSCM moire are described concisely. As application, the method is used to measure the local deformation of poly-crystal aluminum alloy plate and characterize the planar periodic structure of butterfly wing..

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Noncontacting shape measurement for 3-D objects is important in automated manufacturing, component quality control, reverse engineering, etc. Phase-shifting method effectively attains high resolution and high accuracy in analyzing phase information on a projected grating. This technique, however, is difficult to be applied to dynamic condition since usually it requires several images. We developed a digital micromirror device (DMD) camera for phase analysis. In this paper, an one-shot shape and deformation measurement method using a DMD camera is proposed. The DMD camera consists of a DMD, a CCD, and two imaging lenses. In optics of the DMD camera, individual DMD mirrors correspond to individual CCD pixels. The DMD on-off binary pattern can be changed more than 6900 times in one second using an accessory light modulator package (ALP) controller board. Individual DMD mirrors operate as controllable high-speed shutters for corresponding CCD pixels. The four phase-shifted images can be recorded within one frame of the CCD camera. Therefore, shape measurement in dynamic condition can be realized without using a high-speed camera. In order to obtain the 3-D information of shape, multiple reference planes are used to calibrate the relationship between phase value and 3D coordinates. The principle and hardware are presented. In an experiment under dynamic condition, 3D shape information can be analyzed from only one captured image.

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In this study, a method for measuring the strain and stress distribution in structural materials has been introduced. The micro-creep deformation of the pure copper and the residual strains (stress) at the interface between fiber and matrix are measured. Fine model grids were fabricated by electron beam lithography and an electron beam scan of the scanning electron microscope (SEM) was used as a master grid. Exposure of the electron beam scan onto the model grid in an SEM produced the electron beam Moire fringes of bright and dark parts. Un-uniform strain distribution and grain boundary sliding were observed and analyzed. Also residual strain and stress around the fiber of fiber reinforced materials were measured.

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The investigation about the significant effects of stress raisers demands well-defined evaluation techniques to accurately determine the stress on the geometric boundary. While various measuring tools are available, the hybrid method employing the least-squares method integrated with Laurent series representation of the stress function was used to estimate dependable stresses around the circular hole in a tensile-loaded plate out of experimental x-displacement data away from the boundary. Traction-free conditions were satisfied at the geometric discontinuity using conformal mapping and analytic continuation. Results from this approach were closely comparable with those of FEM.

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A new digital moire method of circular and radial gratings for measuring in-plane displacement and strain distributions in the polar coordinate system is proposed. A coordinate-transform technique is introduced which enables the image processing to analyze moire fringes generated by circular and radial gratings. The four steps phase-shifting technique is easily achieved by precisely shifting the computer-generated reference gratings. Basic procedures of in-plane displacement analysis are explained in detail. Two experiments of different crack models for large deformation analysis on cracked rubber sheets are shown. Using a deformed grating, the distributions of in-plane displacements are measured and the distributions of strains can be calculated. And results of the application show that the present method is an efficient method in measurement of soft materials which can endure large deformation.

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This work deals with the development of a full-field extensometric method at a micrometric scale in order to precisely identify the local features of a metallic alloy at the scale of the grain. The full-field method that has been chosen is the grid method that applies a spatial phase-shifting algorithm to a periodic pattern. To mark the sample, the direct interferometric photolithography is used. First, the influent parameters of this technique have been optimized for a digitization of the signal thanks to a white-light interferometric microscope. Measurements of rigid-body motion have been carried out and have revealed parasitic effects that one had to understand and treat. The first mechanical tests are finally introduced.

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According to the theories of material strength, where there is a hole in the structure part, an abrupt change in cross section occurs and the stress distribution around the hole will vary correspondingly. Even the size of hole may be small, it should be concerned in design because the stresses in the vicinity of the hole is always much higher than those faraway from the hole and the structure failure often take place in those positions. Due to the complexity of the engineering problems, it is difficult to obtain the stress field around the hole directly by theoretical derivation. Reflective photoelasticity is a widely used experimental full-field technique for accurately measuring surface strains to determine the stresses in a part or structure during static or dynamic testing. Photoelastic phase-shifting method can be used for the determination of the phase values of isochromatics and isoclinics. Conventional Babinet-soleil compensation method and photoelastic phase-shifting technique were utilized to analyze a specimen with a triangle hole and a circular hole under bending. Three groups of results were obtained by conventional compensation method, 8-step phase-shifting method with reflective-type photoelastic arrangement and FEM (ABAQUS) simulation, respectively. They agree with each other relatively well considering experiment error. The reliability of this combined method can both improve and extend the two conventional methods to be applied to more new fields of stress analysis.

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Micro torsion actuator is widely used in micro torsion reflecting mirror to be one of the important applications of MOEMS (Micro-Optical-Electro-Mechanical system). For fabrication benefits and improving yield ratio, the upper electrodes of torsion actuator are often used as reflecting mirror, too. However, the structure of actuator would be deformed by induced thermal residual stress due to mismatch of thermal expansion coefficients between the upper electrode and structure layer after devices being cooled down to room temperature from hundreds degree process of depositing electrodes layer. And the performance of mirror would be affected by deformation. Therefore, effect of electrodes size and position on deformation is investigated in this work. The FEM software ANSYS is used as analyzing tool. It is found the smaller electrode area would induce less deformation. And the electrodes positioning more close to the torsion axis of actuator would have larger deformation initially. When the upper electrode is more near to the free end, it will have smaller deformation. Effect of dividing the whole electrode into several smaller sub-electrodes on deformation is also discussed. The results show the deformation becomes smaller as the number of divided sub-electrodes increasing. However, as the number is larger than five, the deformation will reach a limit value, that is, the deformation has no significant difference as the number increasing.

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Quasi-static crack propagation in quenching process is investigated through experiment and theoretical analysis. Instantaneous phase-stepping photoelasticity using a CCD camera equipped with a pixelated micro-retarder array is used to measure the stress field around a crack tip in a quenched plate. The result shows that the direction of the maximum principal stress does not act in the direction of perpendicular to the crack propagation direction. The stress field for the problem is then examined by theoretically. The theoretical result agrees well with the one obtained by the experiment for the oscillating crack with small amplitude. These facts mean that the propagation direction of the crack arising in quenching process is not determined by the direction of the maximum principal stress but by that of the minimum principal stress.

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This paper is about Oriented Carrier-Wave in photo-elasticity mechanics. The theory of Photo-elasticity with new oriented carrier-wave is present in this paper, accordingly to the theory we get a new measured principal stress methods finally. By this way the number of photo-elastic stress patters and stress trajectories has been obtained with image processing methods perfectly and highly quality, so that the precision of photo-elasticity method has been improved rapidly, and the advantage in application of optical engineering is well enlarged in the photo--elasticity mechanics field.

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An electro-optic modulated circular heterodyne interferometer using the phase-lock technique for measuring the circular birefringence in chiral medium is proposed. The validity of the proposed design is demonstrated by the measurement of rotation angle of the chiral medium such as a half-wave plate and the glucose sample. The average relative error in rotation angle level of 0.00284° has been obtained for a solid half-wave plate, with a correlation coefficient of 0.9999975 indicates a good linear response. Moreover, the standard deviation in rotation angle level of 0.005275° has been obtained for glucose solutions with concentrations ranging from 0-1.2 g/dl in 0.2 g/dl increments, with a correlation coefficient of 0.99915 between the reference and the measured values. Consequently, the proposed apparatus has advantages of a simpler structure, fewer optical elements, tunable heterodyne frequency, and easy signal processing. The linearity and resolution characteristics of this system are comparable to those previous studies adopting phase sensitive techniques. This apparatus enables not only the measurement of the circular birefringence successfully in the phase-lock technique, but also the integration with previously developed linear birefringence measurement system.

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It has been known that any deviation in the structural and mechanical properties of a living cell can not only affect its physiological functions but also lead to diseases. For example, red blood cells (RBCs) transport oxygen to various parts of the human body while squeezing their way through narrow capillaries. However, in the disease malaria, the parasite invades RBCs and releases proteins that interact with and induce changes to the membrane skeleton of the RBC. Subsequently, these changes will cause RBCs to be stiff and sticky, resulting in the impairment of blood flow which can lead to anemia, coma or even death. In the case of cancer, the affected cells are more deformable than their healthy counterparts, and changes in the mechanical properties of cancer cells may contribute to metastasis. This article will demonstrate the use of biophysical techniques to probe the progressive stiffening and cytoadherence or stickiness of malaria-infected RBCs, as well as the increased deformability of cancer cells. Knowing the ways and the extent to which mechanical properties of living cells are altered by diseases can not only allow us to measure the cellular mechanical property changes in a quantitative way, but also lead to possible new methods of detecting and diagnosing diseases.

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Poly (vinyl alcohol) (PVA) hydrogel is one of the anticipated materials for artificial cartilage. In our previous studies, wear of PVA hydrogel depended on content of proteins in lubricants. The secondary structures of bovine serum albumin (BSA) and human gamma-globulin (HGG) were investigated in circular dichroism spectroscopy to clarify the influence of the protein conformation on frictional properties. BSA and HGG were mainly composed of the alpha-helix and the beta-sheet, respectively. BSA containing the alpha-helix structure showed low friction compared to HGG composed of the beta-sheet structure in mixed or boundary lubrication mode. The alpha-helix structure forms a low shear layer because the alpha-helix structure is easily released from surfaces and low cohesive strength. HGG forms an uniform adsorption layer, but showed higher friction than BSA in the rubbing lubricated with single protein solution. In the repeated rubbing with changing of lubricants from HGG to BSA, however, the final friction was reduced, because an optimum layered structure of proteins was formed. Hence, a layered structure of proteins appears to play an important role to protect rubbing surfaces and to reduce friction. In heat treatment tests, heat-induced BSA showed very low friction because of reduction of the alpha-helix structure. Heat-induced HGG did not show large differences from native HGG, but could not bring low friction with heat-induced BSA. Thus it was shown that the protein conformation has effective influences on friction.

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The aim of this study is to understand the mechanisms of wear reduction of PVA(poly(vinyl alcohol) hydrogel through in situ observation of forming boundary film composed of synovia constituents on the rubbing surface. In this study, reciprocating tester was constructed on the stage in inverted fluorescent microscope. A sliding pair of a spherical reciprocating upper specimen of PVA hydrogel and flat stationary lower specimen of cover glass was prepared. Solution of 0.5wt% sodium hyaluronate (HA) was used as base lubricant and fluorescent-labeled albumin and γ-globulin were used as additives. Rubbing surface was observed through a cover glass of lower specimen and images of rubbing surface were recorded at periodic interval. Lubricants with single protein showed that albumin adsorbed loosely on rubbing surface, whereas γ-globulin adsorbed tightly. When both of albumin and γ-globulin were added to lubricants, thickness of adsorbed layer was increased as compared to that for protein solutions without HA, and lubricant with 1:2 ratio of albumin to γ-globulin at total concentration of 2.1wt% formed the most uniform and stable boundary film. In addition, lubricants in which uniform boundary film was formed showed lower friction coefficient. These results indicate that coexistence of HA and proteins accelerate the formation of boundary film and it is considered that uniform boundary film that is effective in lowering friction is formed in lubricant with appropriate constituents.

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The super hydrophilic polymer brush was prepared by surface-initiated atom transfer radical polymerization (ATRP) of 2-methacryloyloxyethyl phosphorylcholine (MPC) on the ATRP initiator immobilized silicon wafer. The graft density was estimated to be ca. 0.22 chain/nm2 based on the linear relationship between number average molecular weight, Mn and the thickness in the dried state. The contact angle against water was very low in air and the contact angle of air in water was ca.170 deg. This indicated that the air bubble in water hardly attached on poly(MPC) brush surface, indicating a super hydrophilic characteristics. Neutron reflectivity measurements of poly(MPC) brush showed that the grafting polymer chains fairly extended to the thickness direction from the substrate surface in a good solvent such as water. Shrinking of polymer chain in salt solution was not observed by neutron reflectivity(NR). Frictional properties of the poly(MPC) brushes were characterized by sliding a glass ball probe in air and various solvents at room temperature under the normal load of 0.49 N at a sliding velocity of 90 mm/min. Extremely low friction coefficient of poly(MPC) brush was observed in humid atmosphere because water molecules adsorbed into brush layer acted as a lubricant. The small influence of friction coefficient on ionic strength was observed because of the high graft density and zwitter ionic structure poly(MPC).

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The chondrocyte-agarose construct has been employed as an experimental model in the cartilage tissue engineering context. In this study, 15% cyclic compression was applied to the chondrocyte-agarose constructs during their culture period to examine its effects on the extracellular matrix (ECM) biosynthesis and mechanical characteristics of the regenerated cartilage tissue. Cylindrical chondrocyte-agarose constructs with a diameter of 4 mm and a height of 2.5 mm were prepared as test specimens. Chondrocytes isolated from metacarpal-phalangeal joint of steers were seeded in 1% Sigma type VII agarose or 4% Sigma type IX-A agarose to give an initial cell density of 1 x 107 cells/mL, and cultured in sterile culture medium (DMEM + 20% FBS) within a humidified tissue culture incubator. 15% cyclic compression was applied to test specimens at 1 Hz for 6 hour a day during their culture period by a mechanical loading system mounted within the tissue culture incubator. After culture periods of 1, 8, 15 and 22 days, mechanical properties of the cultured constructs, tangent modulus and equilibrium modulus, and glycosaminoglycan (GAG) biosynthesis were evaluated by the unconfined compression test and demethyl-methylene blue (DMMB) assay, respectively. The structural organization of the elaborated tissue was also examined morphologically by the confocal laser scanning microscopy (CLSM). Results indicated that the cyclic compression upregulated the GAG biosynthesis and the tangent modulus in both agarose constructs; however the upregulative effect on the development of collagen fiber network could not be identified. The GAG content and collagen network organization was significantly affected by the characteristics of the agarose construct. Consequently, the development of the mechanical stiffness was more significant in 1% type VII agarose compared to 4% type IX-A agarose.

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This study was conducted to examine whether low reactive-level laser therapy (LLLT) using a He-Ne laser (wavelength: 632.8nm) promotes operative wound healing. Ten-millimeter surgical wounds were created on the backs (thoracic, lumbar and buttock regions) of Sprague Dawley rats, and the rats were assigned to one of eleven groups (n=5). Ten irradiation groups each received one of two different doses (8.5 mW and 2.09 J/cm2, or 17.0 mW and 4.21 J/cm2) for one of five different irradiation periods (every day [from day one to day six following surgery], every other day [days one, three and five following surgery], only on the first day following surgery, only on the third day following surgery, and only on the fifth day following surgery). The other group was the non-irradiation group. Skin was harvested from the dorsal thoracic region seven days following surgery, and skin specimens were prepared in order to examine the rupture strength of the operative wounds in tensile testing. The mean rupture strength in the non-irradiation group was 5.01 N, which was the lowest, and the mean rupture strength in the 17.0 mW every other day irradiation group was 13.12 N, which was the greatest. There were significant statistical differences between the non-irradiation group on the one hand, and the 8.5 mW every other day, the 17.0 mW every day, the 17.0 mW every other day, and the 17.0 mW first day only groups on the other hand.

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Effectiveness of mesh-like interface for percutenous devices was studied with a rat model. The purpose of this study was mechanical and histological evaluation of a percutaneous device model on which a sheet with many small holes was adhered as a mesh-like interface to tissues. The model was prepared by adhering a 0.2-mm thick PMMA sheet with 10 rows × 100 columns of 200-μm laser-processed holes to a machined PMMA cylinder of 10-mm diameter and 6-mm height with a circumference groove. The sheet was placed over the groove and thus provided a mesh-like interface for mechanical attachment. Similar specimens without laser-processed holes were also prepared and used as controls. The specimens were implanted into dorsal skin of rats for 4 weeks. The attachment strength test and histological observation was carried out for the retrieved specimens. The attachment strength of the devices with mesh-like interface was measured as 3.59 ± 3.93 N (n = 10), that was statistically greater than that of controls. Histological observations revealed that collageneous fibers coming from surrounding tissues entered through the holes of the mesh-like interface of the model. This finding confirmed that the mechanical attachment of tissues was realized. Thus the effectiveness of the mesh-like interface for percutenous devices was demonstrated.

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As congenital hip dislocation residual subluxation is the aftereffect of congenital hip dislocation, it is characteristic that the ailment remains. Hip joint disease is typically said to be difficult to treat within the medical orthopedic field. Although on exact cure is desired, when taking into consideration factors such as operation method and the age of the patient, there is still no conclusive method at present because of the differences in medical treatments and Transplant bone of immediately after operation and so on other varying dynamics. In this research, the Salter method for pelvic osteotomy, was adopted. The operation important to performed in order to fully understand the stress states. A comparative examination of the states immediately after the operation and 6weeks after the operation using the Salter method and comparison with a normal joint, was carried out using the 3-dimensinal stress freezing method for analysis. It was found that, the states of stress on the hip joint immediately after the operation and 6 weeks after of the operation, were almost the same as for a normal joint. This finding corresponds to the treatment policy of the medical field for the results of a dynamic examination, and it has therefore been understood that this is a steady dynamically operation method.

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In recent years, because of our aging, the rate of people who show symptoms of gonarthrosis is increasing. The proportion of patients with osteoarthritis, in particular, is the largest among them. The fibula excision method is one method to treat this symptom. However, the exact position and quantity of fibula to be excised depend solely upon the doctor's experience and intuition at the time of operation, presently, no clear, indicative means exist. Therefore, to consider the possibility of excessive burden on the human body, there is a pressing need to determine the stress distribution state of the periphery of the knee joint after the operation. Thus, using the stress 3D freezing method, this research examined the stress distribution states of the periphery of knee joint by changing the position and quantity of fibula to be excised. Analyzing the influence of the fibula that extends to around the knee joint using the 3D stress distribution state, it was concluded that the fibula excision method is effective in improving the condition of osteoarthritis.

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The object of this study is to analyze kinetics and kinematics of knee prosthesis. We have developed a new type of prosthesis which is capable of deep knee flexion. We created a 3D mathematical model incorporating the above prosthesis. Using this model simulation was performed under the simple knee flexion. As for simple knee flexion motion, a cadaver experiment was also performed.We performed the simulation for simple knee flexion to verify the validity of the model by comparing the results with those of the experiment. Our model can calculate the knee motion precisely because in our model not only a femorotibial component but also a patellofemoral component are included, and major muscles, ligaments and tendons are taken into account. From our model, we could calculate contact trajectories and contact forces on the articulating surfaces, ligaments' strains as well as valus-valgus and rotation angles of the knee. When we compared the resultant forces during simple knee flexion, the variation pattern from simulation was in good agreement with that of experiment. And we confirmed the feasibility and usefulness of our model.

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The aim of present study is to establish an automatic system to analysis the maneuvers of fast-start performance in fishes. Fast-starts are brief, sudden accelerations used by fish during predator-prey encounters. We employ frame-by-frame analysis of high speed camera (1000Hz) to quantify midline kinematics during fast-start maneuver. This system includes three steps: First, partitioned the midline into equal interval lengths and decided the intersegmental points in the front image. Second, find out these points in next image using digital image correlation (DIC) and using a spline based curve fitting technique to fit the data above. All the midlines were figured out frame by frame. Third, calculating the kinematics based on the midlines of fish mentioned above. Using this system in carp we have obtained the performance of turning rate, CM (centre of mass) turning rate, CM turning radius etc. The results show this system can obtain more accurate kinematics data.

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In this study, a novel optical interferometric technique called 'statistical interferometry'^<1-3> has been developed. In contrast to the conventional interferometry where the phase is determined in a completely deterministic way, we consider the interference of completely random wave fronts, i.e., speckle fields, and it has been proved that the complete randomness of the speckle field can play the role of a standard phase in a statistical sense. The advantage of the method is that since the phase of the object under testing can be derived in a statistical way, the accuracy of the measurement depends only on the number of data taken to calculate a probability density distribution of speckle phase. This feature permits a simple optical system to achieve measurements with an extremely high accuracy. According to a computer simulation, the accuracy of λ/1000 can be achieved using 40,000 data of the speckle intensity. Statistical interferometry was applied to monitor biological activity or growth rate of plant, aiming to investigate the influence of the environmental pollutions. In the experiments, the plants were exposed to ozone that is the main substance of photochemical oxidant, and the growth rates were measured before and after the exposure. It was clearly observed that the fluctuation of growth rate as well as its mean rate was dramatically affected by the exposure of ozone. By the observation of growth rate of plant with the accuracy of sub-nanometer scale and a time scale of second, it was newly revealed that the fluctuation of the growth rate reflects the biological activity of the plant.

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Welding processes have been widely used for the construction of metal structures. Their reliabilities depend upon the weld quality as well as the weld size. Therefore, various nondestructive inspections have been applied to the welded region, in which the methods with X-ray and ultrasound are widely used for the detection of defects and for the measurement of weld size. However, these methods are too difficult to detect the fusion zone nondestructively, in spite of large demands of its evaluation. Along with the recent application of high strength steel sheet to the automobiles, this problem becomes a critical subject in the spot welds, in which the discrimination of fusion zone called "nugget" from the solid-state welded zone called "corona bond"is strongly demanded. This study focused on the spot welds and aimed to discriminate the nugget from corona bond nondestructively. A new ultrasonic measurement with line focused probe was proposed for the evaluation of the nugget. In the experiment, two types of thin sheet specimens were prepared for the clarification of the acoustic phenomena in the fusion zone. One was the resistance spot welded specimen and another was the gas tungsten arc welded specimen. It was shown by the measurement of these specimens that the sound velocity in the fusion zone is different from one in the base metal and it depends on the inhomogeneous micro structures. This different sound velocity causes different amplitude of reflected waves in the nugget, which also depends upon the measuring condition. From these results, it was shown that the measurement based on the different amplitude and the dependence on the measuring condition enables the nondestructive discrimination of the nugget from the corona bond.

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A tracking procedure for the high-resolution X-ray computed tomography has been developed in order to measure 3-D local strain within a deforming material in high-density. A model sample, which made of a dispersion-strengthened copper with alumina particles and contains artificial micro-pores, was visualized by the synchrotron radiation computed tomography (SR-CT) with in-situ test rig. Tensile loading was applied to the sample step by step. High-resolution tomographic experiment was performed at the third-generation synchrotron radiation facility (SPring-8) in Japan. Gravity center position, volume and surface area in the pores, which were regarded as markers in a tracking procedure, were measured by 3-D digital image analysis. The markers before and after the deformation were provided for registration and macroscopic strain correction before the tracking procedure. The marker tracking was carried out by means of matching parameter that was described as functions of distance, volume and surface at markers. The developed tracking method indicated high tracking ratio and tracking success ratio, which was approximately 100%, up to the macroscopic strain level that exceed in the strain range of practical tracking experiment. The 3-D strain distribution was represented successfully by the tracking results. A combination of high-resolution SR-CT and tracking of microstructural features is effective to visualize interior strain distribution in materials in 3-D.

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This paper presents a methodology to detect, locate and assess cracks in structures using frequency measurements and energy formulation of the vibration theory. Cracks are modelled as a mass-less, infinitesimal, rotational springs with a much smaller stiffness than that of the undamaged structure. The variation in the natural frequency of the defective structure from that of the undamaged structure in each mode is dependent on the size as well as the location of the crack. The location and the severity of the crack are identified by triangulation from changes in natural frequencies in different modes caused by the defect. The proposed methodology is validated by Experimental Modal Analysis (EMA) of a cantilever beam with through thickness cracks of various sizes located at different positions along the length of the beam. Good agreement is obtained in all cases.

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Welding is widely used for construction of many structures. It is well known that residual stress is measured near the bead because base metal is heated near the bead. Tensile residual stress on the surface degrades fatigue strength. Some reduction methods of residual stress are practically used, for example, heat treatment and shot peening. The authors developed a new method for reduction of residual stress using vibration during welding. In this method, single vibration was used. The effectiveness of the method was demonstrated. In this paper, the effect of vibrations with different frequencies on reduction of residual stress is examined. The effect is examined experimentally by butt-welding of thin plates. First, two thin plates are butt-welded using ultrasonic vibrations with different frequencies on each plate. Some plates are welded using single ultrasonic vibration and without ultrasonic vibration for comparison. When thin plates are welded using vibrations with different frequencies, tensile residual stresses are reduced and reduction rate is largest compared with other conditions. Second, two thin plates are butt-welded using ultrasonic vibration and vibration with low frequency. Some plates are welded using single vibration and without vibration for comparison. In this case, tensile residual stresses are reduced and reduction rate is largest compared with other conditions. Obtained results are examined by analytical method.

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Neutron stress measurement can detect strain and stress information in deep region because of large penetration ability of neutron beams. The present paper describes procedure and results in the residual stress measurement of titanium casting alloy by neutron diffraction. In this study, the three axial method using Hooke's equation was employed for neutron stress measurement. This method was applied to the cylindrical shape sample of titanium casting alloy (Ti-6Al-4V). Form the results of this study, this sample has large crystal grain in the inside whole position, it is assumed this large grain was grown up during casting manufacture process. Furthermore, the peak profile used to the stress measurement appears in very weak because of the HCP crystal system of titanium character and effect of large crystal grain. These conditions usually make difficult to measure the accuracy values of residual stresses. Therefore, it had to spend a long time to measure the satisfied data from titanium sample. Regarding to the results of stress measurement, the stress values in the cylindrical sample of three directions is almost same tendency, and residual stresses change from the compressive state in the outer part to the tensile state in the inner part gradually.

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In this paper, both the modal testing method and amplitude-fluctuation (AF) electronic speckle pattern interferometry (ESPI) were used to measure the resonant frequencies, mode shapes, phase distribution and whole-field displacements of composite plates with and without defects. Square- and circular-shape defects of two different sizes were used in the composite plates. Two different stacking sequences of the composite plates were adopted, i.e. [0/90]3S and [±45]3S. Composite plates containing simulated defects located from the 3rd to 6th layer numbering from the top of the plates were fabricated, respectively. It was found that both the anomaly of the AF-ESPI fringe pattern around the defect and the decrease of resonant frequencies due to the defect are feasible ways to detect the existence of the defect. To explain the local effect of the defect at higher frequencies, vibration theory of thin plate with fixed ends for the square shape defect was employed.

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Laser peening without coating (LPwC) is an emerging surface technology to enhance fatigue strength and prevent stress corrosion cracking (SCC) of metallic materials. LPwC was applied to SUS304 austenitic stainless steel and AC4CH cast aluminum alloy samples with a Q-switched and frequencydoubled Nd:YAG laser. Residual stress depth profile over the top surface of the SUS304 sample was precisely measured by a constant penetration depth (CPD) method, which is in the framework of the sin^2Ψ method and can strictly control the X-ray penetration depth into the sample material. By combining the CPD method with high energy X-ray of SPring-8, the depth profile was evaluated non-destructively before, during and after heat treatment up to 673 K (400 ℃). The residual stress in the top surface of the SUS304 sample is entirely compressive despite the direct irradiation of intense laser pulses on the material and the thermal loading. High-cycle fatigue testing was performed for AC4CH samples with and without LPwC, which demonstrated that LPwC significantly prolonged the fatigue life. Replication technique was applied to evaluate the propagation behavior of fatigue cracks on surface. Three-dimensional (3D) images of fatigue cracks were reconstructed by micro tomography (μCT) with phase contrast effect using highly parallelized coherent X-ray of SPring-8. The retardation of crack growth was confirmed in the material with LPwC in the images of μCT.

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Tensile tests were carried out for copper thin films. Three kinds of thin films were fabricated by RF magnetron sputtering. The target power was changed from 10 to 100 W to control the grain size. The grain size increased with increasing target power. The effect of grain size on the deformation behavior under tensile loading was investigated by X-ray method. The residual compressive stress determined by X-ray method increased with increasing grain size. On the other hand, the 0.2% proof stress decreased with grain size. The relation between the applied stress and the X-ray stress can be divided into four regions. In the first region, the X-ray stress increased linearly with applied strain. In the second region, the value of the full width at half maximum, FWHM, increased rapidly with applied strain. Then the stress became constant in the third region. In the final region, the stress and FWHM decreased with applied strain. During unloading, the value of FWHM decreased with stress. For the specimen with fine grains, when the stress became zero, the value of FWHM decreased to an initial value in spite of large plastic deformation. After tensile loading, many intergranular cracks could be observed on the specimen surface. Decrease of the stress and FWHM in the final region comes from the nucleated cracks.

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Wafer topography measurement by using the phase-shifting shadow Moire method has been reported recently. However shadow Moire method is not capable to measure the wafer with a specular surface. In this paper, a wafer topography measurement system with LCD (liquid crystal display) is designed and demonstrated based on four-step phase stepping fringe reflection method using LCD. Wafer bows can be achieved by analyzing the fringe patterns reflected from the specular surface, and film stress can be obtained subsequently by transforming this wafer curvature using a conversion equation such as Stoney's formula. Surface profile of PECVD nitride and oxide coated wafers are measured by a shadow Moire system from the substrate side, and by a fringe reflection system from the coated specular side. A very good agreement between the results obtained from the two methods. Comparing to the result from a commercial profiler, the difference is less than 2μm. This system is especially suitable for stressed films with specular surface. Wafer bow obtained by fringe reflection method is based on full-field information and it would have a better accuracy and better thin film stress characterization

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For the detection of fatigue damage before crack initiation in an austenitic stainless steel, SUS304, we investigated the possibility of the fatigue damage detection and evaluation from the change in the magnetization. The changes in the magnetization before the fatigue crack initiation were observed in the fatigue process at several stress amplitude and stress ratio. It was found that the changes in the leakage magnetic flux density B_z were observed before crack initiation and the location, where the maximum changes in the value of B_z observed, coincided with the location of the stress concentration, where the crack was formed. The experimental results obtained by fatigue tests conducted under the stress ration, R, of -1, and 0.1 showed that the change in the magnetization of SUS304 specimen was depended on the stress ratio. Under either stress ratio, the value of B_z rapidly increased just before crack initiation. When no crack was found, increasing rate of B_z decreased with increasing the number of cycles, and the value of B_z was saturated to a certain value. It was found that fatigue damage before crack initiation can be detected from the change in the magnetization in SUS304 steel.

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The fatigue testing was carried out with specimens containing a deep notch, a bolt hole and bolted specimens of the aluminum alloy 2024-T3, and the ultrasonic measurement with the surface acoustic wave (SAW) was carried out to examine detectability of a crack. The effect of bolt fastening on the detectability of SAW was also examined. The signal from the crack and the notch was detected with fastened condition. The in-process ultrasonic measurement was carried out during fatigue testing with local immersion method by using a water bag for deep notch specimen. The SAW distribution along the crack path line was also observed at 45 degree irradiation by scanning the probe at an interval of 1mm. The SAW distribution was plotted on the photograph containing crack and mean point of SAW distribution lied near the crack path line. The reflection from bolt hole and crack was observed with ultrasonic measurement of SAW with bolt hole specimen. The fretting fatigue failure was observed during the fatigue testing of the bolted specimen. The fatigue life of the bolted specimen was lower as compared to the bolt hole specimen. The in-process ultrasonic measurement of the SAW was carried out for the bolted specimen during the fatigue testing, and the signal from fretting fatigue crack tip was observed before the bolt hole edge. The SAW distribution was compared with that obtained from the photograph and the distance from the bolt hole edge verifies the reflection of the crack.

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We have proposed a new ultrasonic method for measuring internal temperature distribution of heated materials. The principle of the method is based on temperature dependence of the velocity of the ultrasonic wave propagating through the material. An inverse analysis to determine one-dimensional temperature distribution in a heated plate is developed and its validity is verified using a numerical model. In order to demonstrate the practical feasibility of the developed method, a single side of a steel plate of 30 mm thickness is heated by hot water and ultrasonic pulse-echo measurements are then performed for the steel during heating. The propagation time of ultrasonic wave in the heated steel is precisely monitored and used to determine the temperature distribution of the steel. The internal temperature distributions determined ultrasonically agree well with those obtained using thermocouples installed in the steel.

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We studied the microstructure evolution of a martensitic stainless steel (JIS-SUS403) during creep by monitoring ultrasonic attenuation. We applied tensile stress of 120 MPa to the material at 873 K. To determine the ultrasonic attenuation, we used the free vibration technique in combination with the electromagnetic acoustic resonance (EMAR) technique. EMAR is a technique combining the resonant technique with a non-contacting electromagnetic acoustic transducer (EMAT). Incorporation of EMAT in resonant technique greatly contributes to improvement in weak coupling efficiency. The attenuation measurement is inherently free from any energy loss, resulting in pure attenuation in a metal sample. We obtained a series of crept samples with various strains and measured their attenuation coefficients. We estimated the rupture time, t_r, with the modified θ projection and a rupture parameter, P_α, and calculated the estimated life fraction, t/ t_r, from the relationship between creep strain and elapsed time. For measurement of the acoustic characterization, miniature samples were cut out of the crept samples. Furthermore, we observed the microstructure evolution with EBSD (Electron Backscatter Diffraction) and TEM (Trans- mission Electron microscopy). The change in the attenuation coefficient corresponded to the evolution of the dislocation structure. EMAR has the potential to assess the damage advance and to predict the remaining creep life of metals.

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The reliability evaluation is required for subway electric multiple units (EMUs) to guarantee the performance and safety during the operation of EMUs. In this investigation, the EMUs used for over twenty years were selected for the reliability evaluation. Moreover, various types of engineering analysis techniques were used for the current performance and safety evaluation. Several characterization means including nondestructive evaluation (NDE) techniques, corrosion testing, and three-dimensional measurements, were employed for the evaluation of car bodies and bogies. The NDE techniques include ultrasonic testing for thickness change and flaw detection, magnetic particle testing for the detection of surface flaws, and radiography, In order to confirm the changes in dimension of car body or bogies, three- dimensional measurements were performed using the laser tracker. The measurement results were compared with the dimensions in original drawing. Moreover, stress and structural analyses using commercial finite element method (FEM) software provided important information on stress distribution and load transfer mechanisms, and the FEM results were compared with running safety testing results during test running. In this investigation, various advanced engineering analysis techniques for the reliability analysis of subway electric multiple units have been introduced and the results of the analysis have been used to provide the critical information for the criteria of reliability assessment.

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A series of prestressed concrete beams were loaded in three points bending until failure. The waveform acoustic emission signals were recorded. Crack initiation and propagation due to bending were monitored and compared with observation. Based on the relationship between the cumulative energy of acoustic emission and time, the waveform acoustic emission signals were analyzed and disposed by using Gabor wavelet. The research shows that the AE signals of the different damage levels of prestressed concrete beams have the different characteristics in time-frequency domain. The research results will provide some helpful enlightenment for on-line and real-time health monitoring of prestressed concrete structures.

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Deterioration of water-flow regime in a pipeline system has resulted in water-leak accidents due to damage accumulation in pipe materials. Evaluation of water-flow regime in pipeline system is currently in urgent demand. In this study, acoustic emission (AE) method is applied to the evaluation of water-flow regime in an existing PC pipeline, which was inspected and then repaired after water-leak accidents. At three conditions, experiments were conducted. First, a water leak phenomenon was investigated. Secondly, an evaluation of water-drained condition was made in the pipeline. Thirdly, experiments were carried out when the pipeline was filled with water after repairing the water-leak section. AE method was applied to detect signals of water-leak and flow under these conditions. The results show that water-leak in the pipeline system could be quantitatively evaluated by using AE hit activity as well as AE energy. AE hit rate was varied with the situation of the pipeline until the pipeline was filled with water. AE energy showed the same behavior as AE hit rate. When an AE sensor was installed on an air valve, AE energy dropped temporarily as the pipeline was being filled with water. However, when water was filled up to the air valve, the increase in AE energy was confirmed. Thus, it becomes clear that when a pipeline is being filled with water after the repair, the situation of water in the pipeline can be clearly identified through AE monitoring. Discharge evaluation of a damaged pipeline system can be conducted in a short time through AE monitoring.

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Standard penetration test is most popular method as in-situ investigation of embankment of irrigation tank. It is, however, difficult to understand the inner situation from small number of the tests. In this study, the electromagnetic wave and elastic wave investigations are tried to use to understand the inner situation of embankment. To obtain the effective information from the reflected wave, the information about the frequency is used in a similar way to impact echo method for concrete structure. By using the proposed method, the distribution of water contents in the embankment is examined.

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Ageing of infrastructures is an un-avoidable issue. To sustain those as long as possible even with reasonable budgets, proper investigations giving quantitative evaluation of soundness should be carried out at appropriate timing. Acoustic emission among NDT techniques seems quite useful to monitor the global integrity of civil structures since one sensor covers a wider range than other techniques and only damage-related cracks/defects induce the AE activity. In the paper, several damage indices obtained from AE parameters are introduced and such applications as for materials characterization and for in-situ structural evaluation are discussed. Through the applications, it is concluded that AE monitoring has potential to be a crucial monitoring technique contributing to expand the service life of civil structures.

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Cementitious materials are by definition inhomogeneous containing cement paste, sand, aggregates as well as air voids. Wave propagation in such a material is characterized by scattering phenomena. Damage in the form of micro or macro cracks certainly enhances scattering influence. Its most obvious manifestation is the velocity variation with frequency and excessive attenuation. The influence becomes stronger with increased mis-match of elastic properties of constituent materials and higher crack content. Therefore, in many cases of large concrete structures, field application of stress waves is hindered since attenuation makes the acquisition of reliable signals troublesome. However, measured wave parameters, combined with investigation with scattering theory can reveal much about the internal condition and supply information that cannot be obtained in any other way. The size and properties of the scatterers leave their signature on the dispersion and attenuation curves making thus the characterization more accurate in case of damage assessment, repair evaluation as well as composition inspection. In this paper, three indicative cases of scattering influence are presented. Namely, the interaction of actual distributed damage, as well as the repair material injected in an old concrete structure with the wave parameters. Other cases are the influence of light plastic inclusions in hardened mortar and the influence of sand and water content in the examination of fresh concrete. In all the above cases, scattering seems to complicate the propagation behavior but also offers the way for a more accurate characterization of the quality of the material.

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Stack Imaging of spectral amplitudes Based on the Impact-Echo (SIBIE) procedure has been developed at Kumamoto university [1]. This procedure is an imaging procedure applied to the impact-echo (I-E) data. In this paper, an artificial surface-crack was tested using SIBIE and ultrasonics. The test estimated two cases on the depth of surface crack and the effect of water filled in the crack. Comparing estimated crack-depths by the ultrasonic testing with those of the SIBIE procedure, improvement of the crack-depth estimation is demonstrated.

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